Certain electronic and electrical components and devices mounted on printed circuit and wiring boards generate considerable operating heat that, unless controlled, may result in temperature related circuit or component failure. The generally preferred control method is to use a heat sink to transfer component heat to the air.
A heat sink can be made of any material with favorable heat transfer characteristics, such as copper, aluminum or steel. Aluminum is generally preferred because it is inexpensive, easy to work with, lightweight, and has good heat transfer characteristics. The heat sink and heat generating component are usually placed in direct contact with one another to more efficiently cool the component.
In most cases, after the heat sink absorbs component heat, the heat is transferred to the surrounding air by conduction or convection. In order to facilitate heat transfer, heat sinks frequently have "fins" to increase the total surface area that serves to conduct or convect heat.
A typical printed wiring or circuit board may have a number of heat generating devices. That is why it is not unusual to have a number of heat sinks on a single circuit board associated with heat generating devices and components. Because circuits are frequently enclosed in cabinets or other enclosures, a fan is used to move air across the heat sink and facilitate the transfer of heat to the air.
When a number of heat sinks are required, design factors in addition to temperature control must be taken into consideration. When a printed circuit or wiring board requires a number of heat sinks, the area of the board occupied by heat sinks will often constitute a significant fraction of the total board space. Similarly, a significant fraction of the total volume available to house a circuit will be taken up by heat sinks when a number of heat sinks are required. Because the total area required for heat sinks may be significant, the board size is often dictated by heat sink requirements. Another factor designers must consider is total heat sink weight when a number of heat sinks are required. Designers, therefore, must address heat dissipation problems from a space and weight viewpoint in designing electronic equipment in order to produce the highly valued small electronics system that some customers prefer.
Designing heat sinks and arranging them to provide for more efficient thermal performance in a smaller space has, in some instances, created its own set of problems. One such problem is that the amount of working space on the printed circuit or wiring board has been reduced, making it more difficult to assemble the circuit. Another problem is that the mounting surfaces on the heat sink to which the heat generating components are fastened are not as accessible as they were on prior art heat sinks. Prior art threaded fastener secured clamps can sometimes be very difficult to use in fastening electronic components to the heat sinks. In some cases, the most advantageous heat sink geometry does not provide paths for tools to reach screws and other fasteners, thereby preventing this advantageous heat sink geometry from being used with prior art clamps. These prior art devices often require significant time and effort to attach an electrical component, which, of course, adds manufacturing cost and hampers production efficiency. Prior art spring clip designs do not address the problem of mounting components on the opposing sides of a heat sink leg nor do they address the problem of the spring clip detaching from the heat sink or electronic component to which they are supposed to be attached. In such situations where the spring clip detaches from the heat sink or electrical component that they are supposed to be connected, the likelihood of a short increases tremendously.
Accordingly, what is needed in the art is a heat sink design that can efficiently cool a number of heat generating devices or components while utilizing a minimum amount of space on a printed wiring or circuit board and a minimum volume within the enclosure. Also needed in the art, is a component retention clip for such a heat sink assembly, that does not experience the problems associated with the prior art retention clips.